http://www.foxnews.com/politic...-year/
Here's just my own opinions of what is going on-
1) Incumbents are heading for the hills regardless of party due to the general public attitude towards Congress.
2) Dems are abandoning ship because of Obama's health care debacle.
I tend to believe my first theory as both parties have multiple incumbents choosing not to run for reelection with the current atmosphere but I don't feel I'm stretching if I say the second theory is also involved in the first regarding dems.